【问题2】（5 分）
根据网络拓扑和需求说明，完成（或解释）交换机S1 的部分配置
S1#config t
S1(config)#interface vlan 2
S1(config-if)#ip address 192.168.2.254 255.255.255.0
S1(config)#interface vlan 3
S1(config-if)#ip helper-address (11) ;指定DHCP 服务器的地址
S1(config-if)#exit
S1(config)#interface vlan 4
......
S1(config)#interface f1/1
S1(config-if)#switchport mode (12)
S1(config-if)#switchport trunk allowed vlan all
S1(config-if)#exit
S1(config)interface f1/2
S1(config-if)#switchport mode access
S1(config-if)#switchport access (13)
S1(config-if)#exit
S1(config)interface f1/5
S1(config-if)#switchport mode access
S1(config-if)#switchport access (14)
S1(config)#interface f1/9
S1(config-if)#switchport mode access
S1(config-if)#switchport access (15)

根据网络拓扑和要求说明，完成（或解释）路由器R1 的配置：
R1#config
R1(config)# interface FastEthernet 0/1
R1(config-if)#ip address (1) (2)
R1(config-if)#no shutdown
R1(config-if)#exit
R1(config)#ip dhcp pool vlan 3
R1(dhcp-config)#network 192.168.3.0 255.255.255.0
R1(dhcp-config)#default-router 192.168.3.254 255.255.255.0 ; (3)
R1(dhcp-config)#dns-server 192.168.2.1 ; (4)
R1(dhcp-config)#lease 0 8 0 ; (5)
R1(dhcp-config)#exit
R1(config)#ip dhcp pool vlan 4
R1(dhcp-config)#network (6) (7)
R1(dhcp-config)#default-router 192.168.4.254 255.255.255.0
R1(dhcp-config)#dns-server 192.168.2.1
R1(dhcp-config)#lease 0 8 0
R1(dhcp-config)#exit
R1(config)#ip dhcp excluded-address (8) (9)
R1(config)#ip dhcp excluded-address 192.168.3.254
//排除掉不能分配的IP 地址
R1(config)#ip dhcp excluded-address 192.168.4.254
R1(config)# (10) 192.168.3.0 255.255.255.0 FastEthernet0/1
//在以太网接口和VLAN3 间建立一条静态路由